Collecting electrode construction for electrical precipitators



March 17, 1953 w. M. SCHMIDT 2,631,684

COLLECTING ELECTRODE CONSTRUCTION FOR ELECTRICAL PRECIPITATORS FiledNov. 1,v 1949 3 Sheets-Sheet 1 WALTER M ALUQLM SCHMIDT INVENTOR.

F'IIG. Il

ATTORNEYS March 17, 1953 w. M. SCHMIDT 2,631,684

COLLECTING ELECTRODE CONSTRUCTION FOR ELECTRICAL PRECIPITATORS FiledNov. 1, 1949 5 Sheets-Sheet 2 A -30 WALTER MALCOLM SCHMI 34 INVEN I LLLLBY l2 l5 l3 F -G g lO ATTORNEYS March 17, 1953 w. M. SCHMIDT 2,631,684

' COLLECTING ELECTRODE CONSTRUCTION FOR ELECTRICAL PRECIPITATORS FiledNov. 1, 1949 .5 Sheets-Sheet 5 HQ 6 FIIG. 8

WALTER MALCOLM SCHMIDT, INVENTOR.

ATTORNEYS which the liquid flows from the pond.

Patented Mar. 17, 1953 UNITED STATES PATENT OFFICE COLLECTING ELECTRODECONSTRUCTION FOR ELECTRICAL PRECIPITATORS Walter Malcolm Schmidt, LosAngeles, Calif., as-

Signor to Western Precipitation Corporation,

6 Claims. 1

The present invention relates generally to the art of electricalprecipitation and apparatus for use in the separation of suspendedmaterials from gases; and it relates more particularly to collectingelectrodes in which a thin film of liquid, for example water, is passedover the surface of the collecting electrode upon which the material iscollected or precipitated. H

The invention in its broad aspects is concerned with liquid-flushedcollecting electrodes which provide an extended surface upon which thesuspended material is precipitated. Usually and typically thesecollecting electrodes take the form of vertical pipes or tubes of whichthe inner surface is the vertically extending collecting surface. Thegas is passed vertically through the collecting electrode pipes, and anopposing electrode, maintained ata relatively high potential, extendscentrally within each pipe. The spacing between the two electrodes ismaintained as uniform as possible.

It has been common practice to place a number of collecting electrodesof this character within a housing or shell which supports ahorizontally extending header plate upon which the collecting electrodesare supported. Water or other suitable liquid is supplied to the upperends of the collecting electrodes and a thin film is formed inside theelectrodes that flows down their inside surfaces.

Ordinarily, both the upper and the lower ends of the tubular electrodesare provided with terminal sections of larger diameter than the centralcollecting portion in order that-the liquid film may be formed andbroken at locations at which the electric field is reduced in strength.This enlargement of the tubular elements prevents arcing over betweenthe electrodes and favors maintaining continuity of the liquid film.

- Anearly precipitator of this general type is shown in Crowder et al.Patent No. 1,968,334

issued July 31, 1934. Inthis patent the header plate has a liquid-tightconnection with the housing and with the several tubes so that a pond ofliquid may be formed on the header plate to supply liquid to the upperends of a plurality of collecting electrode tubes. The upper terminalsections of the collecting electrode tubes are fiared outwardly andtheir top edges form weirs over It is particularly to be noted that inthis construction it is necessary not only to level each combinedelectrode and weir with respect to the pond surface but that all weirsmust be placed as closely .as possible at exactly the same elevation inorder to equalize flow of liquid in each electrode. Where the terminalsections are formed integrally with the main collecting portion of theelectrodes, the movement of the weir to level it with respect to thepond moves the remainder of the electrode, and vice versa.

As a matter of practice, it has been found extremely difiicult andtime-consuming, and therefore expensive, to obtain equal flow of liquidin all electrodes of a group supplied from a common pond. The tubes mustbe individually leveled and raised or lowered, and in many cases theweirs must be hand finished in place in order to obtain satisfactoryoperation. Some concept of the enormous amount of work involved ininstalling a precipitator of this type may be had when it is understoodthat the number of pipes to be leveled may run up as high as one to twohundred.

Even if the tubes can be satisfactorily leveled at the time ofinstallation, this condition may not continue to exist. Precipitatorinstallations are large and heavy and a certain amount of settlement inthe foundations often occurs. Also, they usually operate at relativelyhigh temperatures, and relative expansion and contraction of the partstakes place as a result of the operating temperatures. These conditionsfrequently combine to destroy the delicate adjustment of the tubes andit is found that some tubes are receiving little or no liquid and othersconsiderably more than their share.

Viets Patent 2,397,302 issued March 26, 1946, and Schmidt et al.2,412,912 issued December 17, 1946, disclose construction in which aseparate weir ring is provided surrounding the flared upper end of eachcollecting electrode, the weir rings being individually adjustable andmovable with respect to their electrodes. Various types of bafile meanshave also been provided to form a quiescent zone in which the liquidfilm is formed. While these devices have resulted in considerableimprovement in the operation of liquid film precipitators, they bothhave the objections noted above due to the necessity of accuratelyleveling a plurality of weirs in a common pond, and also have thefurther objection of being relatively expensive because of the machinework necessary to fit the weir rings to the electrode pipes. These fitsbetween the pipes and their weir rings must be relatively tight in orderto prevent leakage and to leave no interruption in the surfaces whichmight break the continuity of the liquid film. On the other hand, if thetolerances are too close, then the range of move- 3 ment of the weirring relative to the electrode is correspondingly limited.

Other types of construction are shown in White Patent 2,192,249 issuedMarch 5, 1940. In this patent various types of film establishing meansare shown. Both overflow and spray types are used, but primarilyreliance for forming the liquid film in each case is placed upon anannular orifice of such dimension that a film of liquid may bemaintained by capillary action between the sides of the orifice. Forthis purpose, the upper terminal section or" the tube is flaredoutwardly and formed integrally with the main portion. Within the flar dportion is a member which forms one side of the orifice and which alsoshields the orifice from the gas stream to permit establishment of thefilm in a quiet zone. The shield or spray ring, or other film formingmember is rigidly mounted upon the upper flared end of the tube, or isformed integrally therewith. In this type of construction, littlereliance is placed upon individual leveling or elevational movement ofthe weir or tubes. A difficulty found with that construction has beenthe fact that under some conditions the annular orifice forming the filmbecomes clogged and as a result the water film is not formed uniformlyaround the entire surface of the tube, but has breaks in it which mayextend for the full length of the tube.

Hence, it becomes a general object of my invention to provide anelectrode construction for a liquid film precipitator in which weirmembers can be leveled and elevated with a minimum of time and effort,and a minimum of adjustment of the weir members is required in order tomaintain a continuous film of liquid in each electrode.

It is also an object of my invention to provide a collecting electrodeconstruction in which the film is initially formed evenly andcontinuously around the collecting surface, and the flushed surfaceitself is free from interruptions or discontinuities which cause anybreak in the continuity of the liquid film.

An additional object is to provide means for supplying liquid to eachelectrode at a substantially constant rate, independently ofaccumulations of foreign matter in the liquid supply.

These and other objects of my invention have been accomplished byproviding, at the top end of an electrode, a member that forms a liquidweir, the downstream surface of this weir-forming member being insubstantial alignment with the collecting surface of the electrode. Theweir member has wall means around the full periphery of the weir to forma reservoir space adapted to hold a body of liquid that overflows thatweir. The liquid, ordinarily water, is supplied-separately to eachindividual reservoir space and weir. In this way the elevation of eachweir is entirely independent of the elevation of each'other weir, aseach weir is supplied from its own pond separately from all others.

Between the electrode and the weir member there is a liquid-tight jointyet one allowing limited relative movement of the members. Fasteningmeans are provided for holding the weir member in place, this meanspreferably comprisin a plurality of screws or bolts by which the weirmember may be leveled upon the upper end of the electrode withouteffecting any movement of the electrode itself or of other weir members.g r 7 Among others, I show and describe herein a accuses preferred formof sealing means to produce a liquid-tight joint between the electrodeand weir member, consisting of a deformable gasket. This same gasket isshown and claimed broadly in the copending application of Lance Hardy onConstruction of Water-Flushed Electrode for -lectrical Precipitator,Serial No. 124,820 filed November 1, 1949, and having common ownershipwith this application.

How the above objects and advantages of my invention, as Well as othersnot specifically referred to herein, are attained will be more readilyunderstood by reference to the following description and the annexeddrawings, in which:

Fig. l is a fragmentary view taken inside a precipitatcr housing showingin elevation several tubular collecting electrodes constructed accordingto my invention, portions of the apparatus being broken away for betterillustration;

Fig. 2 is an enlarged fragmentary plan view showing a single collectingelectrode of Fig. 1 in plan with portions of adjoining electrodes;

Fig. 3 is a further enlarged fragmentary vertical section through theupper end of the collecting electrode structure, as on line -3-3 of Fig.2;

Fig. 4 is an enlarged section and elevation "of the flexible nozzlesupplying liquid to each weir;

Fig. 5 is a partial plan view of a modified form of my invention;

Fig. 6 is a fragmentary'vertical section online 6-43 of Fig. 5;

Fig. i is a partial plan view or another embodiment of my invention; and

Fig. 3 is a fragmentary'vertical'section on line 88 of Fig. '7.

A plurality of tubular collecting electrodes in are shown as extendingvertically through and supported by header plate l2, it being understoodthat these electrodes are ordinarily mounted within an enclosingprecipitator housing or shell provided with gas inlet and gas outletmeans (not shown) at opposite sides of the header plate. Header plate [2is supported upon the housing by any suitable means "and subdivi'des thehousing in such a manner that the portion or" the housing "interiorbelow header plate 22 forms in effectan inlet chamber which distributesthe gas to the bottom ends oi? tubular electrodes iii. The gas riseswithin'the electrodes into the space above header plate 1'2 and leavesthe housingthrough the gas outlet means. Details of the housing and itsgas inlet and outlet means are not illustrated in detail because theymay takemany various forms and are well known in the art; but referencemay be made to the above-mentioned Patent No. 1,968,334 for disclosureof one type of housing.

Each collecting electrode ill comprises a pipe or tube of suitablelength and diameter, the diameter being substantially uniform. 'The axesof all'pipes arevertical, or substantially so. The

upper end of the tube'extends abovehe'aderplate l2, as shown in greaterdetail in Fig.3, and is provided with a surrounding flange it by whichthe electrode is suspended. Each of the several electrode-receivingopenings 53 in header I2 is of slightly larger diameter than theelectrode, and resilient gasket (5 is'interposed between electrodefiange i l and the upper surface of the header plate to provide afiuid-tightseal between the electrode and the header plate. The weightof the tube resting upon the gasket forces it into intimate contact with7 both the I header plate and the electrode; and it is preferable toincline flange l4 downwardly in order to confine the gasket and improvethis contact.

The inside surface of each tubular electrode I is the collecting surfaceof the electrode and it can be seen from the drawings that this innersurface is of extended area. It is a comparatively smooth, continuoussurface in order that the liquid film formed thereover, as will befurther described, may be maintained as a continuous film.

It is to be understood that my invention is not necessarily limited to atubular electrode; but I show and describe it in conjunction with suchstructure as liquid-flushed electrodes are most usually tubular. If thecollecting surface is flat, as provided by a plate, or otherwise shaped,

then it will be self-evident from the following description to personsskilled in the art how my invention can be altered in its details toconform to collecting surfaces of other than cylindrical configuration.

On the upper end of each electrode I 0 is a weir member I8. The weirmember has an inner wall I9 which is flared outwardly at its upper endand at its lower end is substantially the diameter of electrode Ill sothat the collecting surface of the electrode and the inner surface ofthe weir member over which the liquid film flows are in substantiallyvertical alignment, as illustrated particularly in Fig. 3. The top edge20 of the inner wall I9 is suitably finished, as by grinding, so that itlies in a single plane. This edge 20 forms a weir over which liquidflows to form the film flowing down the collecting surface of electrodeID. The film-covered inner surface of wall I9 is referred to herein asthe downstream surface of the weir member.

Liquid for this purpose is contained in an annular reservoir space 2|formed entirely around the outside of weir 20 by outer wall means 22,which is preferably an integral part of weir member I8. Since weir 2D isannular in shape, wall 22 is also annular, except for the formation inthe wall of bay 24 which provides a space for the introduction intoreservoir 2! of fluid inlet pipe 26. The end of pipe 26 carries a nozzle2! that directs .the entering stream of water tangentially at the bottomof the reservoir space to minimize turbulence. A common supply pipe 28(see Fig. 1) extends horizontally above a row of electrodes and isconnected to a number of individual inlet pipes 26, each of the lattersupplying liquid to only a single electrode reservoir. The rate ofliquid supply is controlled by the size of pipes 26 and the pressure inmanifold 28.

It has been found by experience that the body of liquid in reservoir 2|should be free from turbulence or motion at its surface where the liquidoverflows weir 20. For this reason nozzle 21 opens to the reservoirspace at the bottom thereof and the reservoir preferably tapers upwardlyto form a constricted top opening between the weir and the surroundingwall 22.

Nozzle 21 is preferably made of an elastic material, as for examplerubber. In a preferred form shown in Fig. 4, it tapers from each end toa constricted central portion 21a like a Venturi tube. One advantage ofthis construction is that the nozzle is flexible and so can be easilyinserted in the reservoir space and conform to it. But the principaladvantage is that by increasing the rate of liquid flow to the nozzle,pressure can be built up in the initial'section.

21b behind the constricted opening 21a and thereby the nozzle can beexpanded slightly. This breaks loose any accumulated sediment andflushes the nozzle so that it is self-cleaning and can be made todeliver liquid at a substantially constant rate at all times. The taperat the exit side of the central constriction 21a is optional and ispreferred in order to provide a chamber in which the liquid velocity isreduced after leaving opening 21a and before actual discharge from thenozzle into the pond of liquid around'the weir. This serves to reduceturbulence in the pond. Without this terminal portion, the exit velocityfrom the constricted midsection may create objectionable turbulence inthe reservoir pond and increase the rate of flow over the weir above theminimum required to keep the film unbroken around it.

Resilient gasket 3| is interposed between weir member I8 and the upperend of electrode ID in order to form a liquid-tight joint between thesetwo members. The gasket is deformable, and preferably resilient, so thatthe weir member can be moved relative to the electrode in order topermit leveling weir 20 to bring the plane of the weir into a trulyhorizontal position without moving the electrode below. In order toadequately confine gasket 3I and force it to project into the electrodewhen it is deformed, it is desirable to providethe weir memberwith agasket-receiving recess 32 formed between the lower portion of wallmember I9 and an external flange or wall 25.

Adjustment of the position of the weir is accomplished by the fasteningmeans which holds the weir member in place on the electrode. Thisfastening means comprises plate 34 surrounding the electrode and bearingagainst the under edge of electrode flange I4. The central opening inplate 3 4 is sufficiently large to receive gasket I5 between the plateand the electrode wall so that the plate forms a means for confining thegasket against outward movement as a result of the weight imposed uponit by flange I4. Plate 34 has fastened to it a plurality of upwardlyextending bolts 35 each provided with a nut 35 and a lock nut 3'1 at itsupper end. Each bolt 35 passes upwardly through a suitable opening in alug 38 on the rim of weir member I8.

When the electrodes are placed in position, they are aligned verticallyby any suitable mean engaging them at or near their lower ends. As anexample of such means, there is shown in Fig. 1 an openrectangular gridconsisting of bars 45 extending at right angles to each other andpassing between successive electrodes I9. At the intersections of bars4!], are mounted short, vertically extending plates 42 which havethreaded bores to receive adjusting screws 43. Screws 43 are providedwith lock nuts 44 to hold them in adjusted position. By means of thisarrangement, which is shown in greater detail in Viets Patent No.2,397,302, the lower end of each collecting electrode can be moved intoand held in the desired position to make the electrode vertical. Thereis suflicient flexibility in the supporting connection between headerplate I2 and flange l4 to permit movement of the electrode for thispurpose.

After the collecting electrodes are in place, the discharge electrodes45 are installed. These may be wires of relatively small diameter ortwisted rods with peripheral portions of relatively small radius tofacilitate corona discharge therefrom when the discharge electrode ismaintained at a 7 sufficiently high potential relative to the collect?ing electrode. Discharge electrodes 45 are posiv tioned axially of thecollecting electrodes and are supported from their upper ends bysuitable frame members 46 and 4] attached to cross beam 48 which issuitably supported, by means not shown, to insulate it from thehQus-ing. At their l w r ends, electrodes 45 are engaged by spacers 50attached to frame member 5| in order to hold the discharge electrodes inproper alignment with respect to the collecting electrodes. If desired,a weight v52 may be attached to the lower end of each dischargeelectrode to tension the electrode.

Since it is desired that the l uid film be broken, as well a esta l shd. at a poin here the electric field is of reduced strength, the lpw rend of each collecting electrode may be provided with a removable ring55. The ring is preferably recessed on its inner surface an amount equalto the thickness of the Wall of tube It in order to receive the lowerend of tube L0, as shown in the right-hand side of Fig. 1, and thebottom portion of the ring is then fiaredcutwardly at 56 so that theinside diameter of the lower end 56 is of substantially greater diameterthan the diameter of the major portion ,of the electrode. By virtue ofthe recess in the ring, the inner surface of the ri g forms a flushjoint wi h t e n r c l ecting surface of the electrode pipe and there isthus provided a substantially smooth, continuous surface over which theliquid film flows. The liquid then drops off ring 55 at the lower end,which is the point of greatest diameter. Each ring has a plurality ofset screws 51 by which it is fastened to electrode tube 10.

After a collecting electrode 10 has been placed in position, gasket 3|is placed on its upper end and then the weir member is placed inposition with the upper ends of bolts .35 extending above the weirmember to receive nuts 35, The gasket is shaped so that a small portionof it initially projects beyond the inner surface of members [0 and 9.as at 31a in la As uts 36 a e t ten d, the first action is to bringplates 34 snugly against l n e 14. If any o t 6 :is urther tighte ed ona bo t. e ir m r a d ol ec n e ect ode e drawn to ether a the i e wherethe nut is being ht n dh s move ent o he weir member relative to theelectrode compresses gas, t i a d a mal P91 9 o it isordiea ilyeroutwardly th u the a ow ap et een the inner surface of the weir memberand the col ecting surface of the electrode proper. This addition to theportion which originally projects beyond the collecting surface ofelectrode I1 21 8..-

cause of the shape of the unstressed gasket. Any

one or more of nuts 35 may be tightened to i111.- prove the liquid-tightcharacter of the seal pro-.- v d d y a k 1 a d to in Weir 0 nto a trulyhorizontal position. This adjusting move-- ment of weir 20 takes placewithout any move..- msnt f ect de o hat the erti al pos tioning of thetube is not altered by adjustingthe weir. in a horizontal position,liquid in reservoir 2! overflows the weir at a uniform rate at allpoints and a continuous liquid film of vsubstandtially rm th ess s es lshed and m intained. around the entire circumference of wall I9. Thisfilm then flows smoothly over the inner downstream surface of the wallmember J9 Each i s ed ind p nde l o eve o he weir- Since each weir hasits separate and individual liquid s pp y f o it o eser oi 21. p per opati n 1 1 e is ind pend nt of he e evation o the weir ai e t others Thequail 8 t y o l q d flow n er it is rmined no b the elevation of theweir with respect to the surface of a common pond supplying severalweirs,

as former y, but only by the rate of liquid flow through nozzle 21.

When the weir member has been brought into a level position, someportion of gasket 3!, as indicated by the dotted lines at 3w, projectsoutwardly beyond the collecting surface and the inner surface of wall[9. This projecting portion from the gasket is removed in any suitableway, as for example by a portable power driven grinding wheel. Whenfinished off in this manner, the final shape of the gasket is as shownin solid lines in Fig. 3 and the exposed inner surface of the gasket isa smooth cylindrical surface which is flush with the downstream surfaceof the weir l9 and the collecting surface of electrode member itimmediately above and below it respectively. The co-pending case ofLance Hardy referred to above contains claims to a collecting electrodeassembly of which this preferred form of sealing means is an element andalso claims to the described method of finishing this sealing member.

There is shown in Figs. 5 and 6 a modified form of my invention which inmany respects is similar to the form previously described. In thisembodimerit, the tubular electrode it is supported upon header plate 12by a plurality of lugs 6c welded to the outside surface of theelectrode. Each opening 13 in the header plate has a plurality ofrecesses or bays 13a of a slightly reater length than lugs to so thatthe electrode may be raised upwardly through opening 53 when each lug5i] is in registration with a recess i311. Then by rotating the tube afraction of a turn about its longitudinal axis, lugs fill are brought torest upon the top surface of header plate [2.

The gap between the electrode and header plate I2 is sealed by annulargasket 6! which is made of rubber or other similarly resilient material.The gasket rests upon header plate I2 and in turn weir member 18a restsupon the top surface of the gasket so that the gasket provides a fluidtight seal.

Weir member la is similar in general to the weir member is describedabove. It is provided with an inner wall is having a top edge 20 whichprovides a weir over which liquid flows downwardly into the electrodeiii to form the liquid film on the collecting surface of the electrode.Surrounding weir 25 is an annular wall 22 forming the reservoir space 25within which a pond of liquid is maintained to supply liquid to weir 26.Liquid is introduced to the pond through supply pipe 25 and a nozzle 52arranged as previously described. Nozzle 62 is a simplified form ofnozzle. It is the same as nozzle 2'5 except that the terminal section ofoutwardly increasing diameter is omitted. It is made of rubber or otherflexible material so that it can be expanded by an increase in internalpressure and any @Ccumulation of sediment or the like can be brokenloose and washed out.

Weir member its differs from the form of Fig. 3 by the omission ofdependent flange 25 and the continuation of inner wall [9 downwardly toform a flange lilo which fits snugly within the upper end its of thetubular electrode.

The outer surface of flange Ida and the inner surface of the electrodesection [0a are machined to fit snugly within each other in order toprovide a substantially fluid-tight connection between the two membersat this point. At the same time, a limited amo n f movemen i pe tedetween these two parts in order to level the weir member independentlyof the electrode. In this form of the invention, the elements we andElla weir member is leveled to bring weir 2% into a truly horizontalplane. This is accomplished by tightening one or more nuts 36 onadjusting bolts 35 which in this form of the invention are attacheddirectly to header plate i2 rather than to a separate plate, as in Fig.3. By tightening or backing on selected ones of nuts 35, the weir membercan be brought into a level position without necessitating any movementof electrode it. At the same time, the weir member is brought down intosnug engagement with the top surface of gasket 6i.

Figs. 7 and 8 illustrate another embodiment of my invention utilizing adifferent type of weir member but employing certain features forconstruction and support of the tubular electrode disclosed above. Inthis form, the upper end section 10a of the electrode is finished on itsinside and is provided on the outside with a sur-- rounding, inclinedflange It by which the electrode is supported. Gasket i5 is interposedbetween flange l4 and header plate 12 to provide a fluid-tight seal ofopening [3 in the header plate through which the electrode passes.Gasket i5 is confined between flange i l, the wall of electrode sectionMia, and the header plate with the weight of the electrode resting uponit.

In this embodiment of my invention, weir member l8b is formed of sheetmetal by a spinning operation, or the like. The weir over which theliquid flows to form the liquid film is provided at 20a by an upwardlyconvex section of the metal sheet which continues on at one side to formthe downwardly and inwardly converging wall H! which provides the downstream surface of the weir.

Around and outside weir 20a, the sheet metal is formed with a U-shapedbend which provides the reservoir space 2|a and the outer wall 22athereof, wall 22a rising higher than weir 20a. Water is supplied to thereservoir space by line 26 and nozzle 62, though a nozzle 21 may be usedif desired. Wall 22a has no bay as at 2% in Fig. 5.

The inner wall section [9 of the weir member continues on downwardlyinto a substantially cylindrical section l9?) adapted to fit snuglywithin end section Illa of the electrode. If desired, the inner surfaceof electrode section Illa may be slightly tapered downwardly by a fewthousandths of an inch per inch in order to improve the tightness of thefit between the weir member and the electrode surface and at the sametime to allow the weir member to tilt slightly with respect to theelectrode. Being of relatively thin sheet metal, the weir member candeform slightly as it is jammed down into the end of the electrode inorder to conform thereto, and to give a, fluid-tight character to theseal between it and the electrode. No sealing means other thanoverlapping sections llla and lab of the electrode and weir memberrespectively is provided to obtain a liquid-tight joint.

In this form of the invention, no screws or bolts are provided forleveling the weir member. This can be done by laying a board or otherprotective member across weir 20c and tapping it I10 lightly with ahammer until the weir is brought into level position. The fit betweenthe weir and electrode is such as to permit a limited amount of thismovement independent of the electrode for leveling the weir. a

In view of the foregoing, it will be understood that various changes inthe design and arrangement of the parts of my improved electrodeconstruction may be made by persons skilled in the art without departingfrom the spirit and scope of my invention. Consequently, it is to beunderstood that the foregoing description is considered as illustrativeof, rather than restrictive upon, the appended claims.

I claim:

1. A collecting electrode construction for a liquid-flushed electricalprecipitator, comprising: a tubular electrode member providing avertically extending collecting surface of cylindrical shape; an annularweir member extending upwardly above the electrode member and having aninner wall of which the top edge provides an annular Weir of largerdiameter than the electrode collecting surface, the inner wall having aninterior surface extending downwardly from the weir to a diametersubstantially equal to that of the electrode collecting surface;impervious wall means formed integrally as a part of the weir member andextending above and around but spaced from the periphery of the weir toform an isolated space adapted to hold a body of liquid having accessonly to said one weir to overflow the weir; leveling means engaging theweir member for leveling the weir independently of the electrode member;and a resilient gasket member interposed between the upper end of theelectrode member and the lower end of the weir member with its exposedinterior surface filling the gap between the Wetted interior surfaces ofthe inner wall and the electrode member in continuation of saidsurfaces.

2. A collecting electrode construction for a liquid-flushed electricalprecipitator, comprising: a cylindrical electrode member providing aertically extending interior collecting surface generally of cylindricalshape; and a detachable annular weir member supported above the upperend of the electrode member and concentric therewith, said weir memberhaving an inner wall of which the top edge provides an annular weir oflarger diameter than-the electrode collecting surface and the interiorsurface extends downwardly and inwardly from the weir to a diametersubstantially equal to that of the collecting surface at the upper endof the electrode, and an impervious outer wall formed as an integralpart of the Weir member and extending around and spaced outwardly fromthe periphery of the weir to form a reservoir space adapted to hold abody of liquid having access to said weir to overflow the weir toestablish a liquid film on the interior surface of the inner wall, saidreservoir space being cut off by said outer wall means fromcommunication with the space outside the outer wall means at all pointsbelow the level of the weir.

3. A collecting electrode construction as in claim 2 that also comprisessealing means that form a liquid-tight joint between the electrodemember and the weir member while permitting limited tilting movement ofthe weir member relative to the electrode member and that directs theliquid film downwardly to the collecting surface of the electrodemember.

4. A collecting electrode construction for a liquid-flushed electricalprecipitator, comprising: an electrode member providing a verticallyextending collecting surface of extended area; a weir member having aninner wall providing a liquid weir above the electrode member forforming a liquid film that flows down over said collecting surface;impervious outer wall means formed as an integral part of the weirmember and extending around the periphery of the weir downwardly from alevel above the weir to form a reservoir space adapted to hold a body ofliquid for overflowing only said weir, said space being out 01f by saidouter wall means from communication with the space outside the outerwall means at all points below the level of the weir; and elasticdeformable member engaging both the electrode member and the weir memberto provide a liquid-tight seal between the two members while permittinglimited relative movement of the weir member.

5. A collecting electrode constructionilas in claim 4 that alsocomprises means for introducing liquid into said reservoir space,including a tangentially directed, elastic nozzle located adjacent thebottom of said space and expandible' upon an increase in fluid pressureto increase the size of the fluid passage through the nozzle and. flushout accumulated particles of foreign matter.

6. A collecting electrode construction for a liquid-flushed electricalprecipitator, comprising: an electrode member providing a vertically ex-12 tending collecting surface of extended area; a weir member having aninner wall providing a liquid weir above the electrode member forforming a liquid film that flows down over said collecting surface;impervious outer wall means formed as an integral part of the weirmember and extending around the periphery of the weir downwardly from alevel above the weir to form a space adapted to hold a body of liquidfor over- REFERENCES CITED The following references are of record in thefile of this patent:

UNITED STATES PATENTS Number Name Date 1,329,817 Wolcott Feb. 3, 19201,339,480 Schmidt May 11, 1920 1,442,052 Dane Jan. 16, 1923 2,269,664Hallerberg Jan. 13, 1942 2,412,912 Schmidt et a1. Dec. 17, 1946

